Sir, The proposal by the consultancy Europe Economics that the most cost-effective way of reducing carbon emissions within the European Union involves a tax “on the consumption of primary fuels in proportion to their carbon content” would require a unanimous decision by all 27 member states if it were to be implemented (“Fight climate change with tax not targets, say economists”, January 21). This requirement for unanimity is unchanged by the Lisbon treaty.

It would be interesting to know whether Europe Economics would favour a move to qualified majority voting in this area. It would be even more interesting to know whether Open Europe, the organisation that commissioned the study, is in favour of such a change. You describe the latter organisation as favouring a “loosely structured, economically liberal EU”. The reduction of carbon emissions within the EU may well be one of the many cases where loose structures and economic liberalism are in fundamental conflict.